Tools for prying objects apart or for removing one object from another (such as a nail from a piece of wood) are quite common. Typically, a prying tool is of a robust metallic design and coarse construction, lending it high strength in most situations but not providing as much utility in situations where more careful movements are required.
Commonly, pry bars (or crowbars) are of elongated design, constructed of heavy-gauge steel and having one flattened end and one curved end with a flattened terminus. At either or both of the ends of the pry bar, the flattened portion may be configured with a notch for grasping and removing nails embedded in wood or other materials. Similarly, a hammer having a nail-removing claw may include a tapered slot configured to grasp a nail. In each case, the prying tool (be it a hammer, a pry bar, or another specialized tool) often utilizes the nail-grasping portion in conjunction with an integral fulcrum to lever a nail or other fastener out of the material in which it is lodged.
In many contexts, a pry bar, hammer, or other prying tool is used to remove fasteners other than nails. For example, in flooring removal applications, such as carpet removal, it is quite common for the carpet underlayment to have been fastened to the floor material (typically wood) with staples. Because the underlayment is usually a soft padding material (such as urethane foam), when it is removed, the fastening staples remain embedded in the floor material, requiring removal. Staple removal is a task that is becoming more common in many structural renovation and/or demolition projects, especially those in which the substrate material should remain intact, as staples replace nails and other types of fasteners as the fastener of choice in many tacking applications.
However, a traditional pry bar or hammer is often not the right tool for such a job, and the staple removal operation is left incomplete or is not accomplished efficiently. For example, the prying member of such a tool may be too large to engage the staple crown properly, such as to provide adequate leverage for removal. Additionally, if care is not used during staple removal with such a tool, one or both legs of the staple may break from the crown and remain lodged in the material, or the crown itself may snap, such as due to uneven distribution of upward force when leverage is applied, or lateral force when the tool engages the staple, and so forth.
As another option, a specialized staple-removal tool (or staple puller) may be utilized, yielding a potentially more effective removal operation. In this case, however, the specialized tool design may require additional labor cost, with the tradeoff for complete staple removal being a slower removal process.
Other factors complicating an efficient and expedient staple removal process includes erratic or non-uniform staple size, placement, density, and/or alignment over a given area, non-uniform crown clearance from the substrate material, and so forth. Also, in many applications, it is desirable to remove staples from a substrate material in a manner that not only leaves the substrate installed (such as wood flooring), but also preserves or minimizes damage to the surface thereof (such as if it is desired to re-use, or even refinish, the wood flooring).